Rotary shaving heads of this type are known from DE-AS 11 21 506, which corresponds substantially to U.S. Pat. No. 3,125,808, and their performance is competitive with that of vibration shaving heads. The advantage of rotary shaving heads as compared with vibration shaving heads is that they are better capable of catching and shaving long hairs. The cutter blades have contact faces which move along the cutting plane of the shear plate, cutting edges being sitauted at the front viewed in the given cutting direction. Thus, the shaving head is intended for one specific direction of rotation of the rotary cutter. When the drive motor is a single-phase synchronous motor, this motor, must be provided with an anti-reversal device which inhibits or blocks rotation in the opposite direction, i.e. a direction opposed to the orientation of the cutting edges of the cutter blades. The use of an anti-reversal device enables unidirectional operation to be obtained but has the disadvantage that the anti-reversal device is an additional part and produces annoying noise.